Stabilization of hydrocarbon



United States Patent Ofifice 2,734,814 Patented Feb. 14, 1956STABILIZATION OF HYDROCARBON DISTILLATES Ralph B. Thompson, Hinsdale,Ill., assignor to Universal Oil Products Company, Chicago, Ill., acorporation of Delaware No Drawing. Application June 26, 1952, SerialNo. 295,821

13 Claims. (Cl. 52-.5)

This invention relates to the stabilization of hydrocarbon distillatesand more particularly to a novel method of retarding deterioration ofhydrocarbon distillates heavier than gasoline.

Hydrocarbon distillates heavier than gasoline are utilized primarily forburner oils and lubricating oils. These hydrocarbon distillates tend toundergo deterioration in storage and become discolored, form sediment,and undergo other undesirable reactions. The present invention isdirected to a novel method of retarding this undesirable deterioration.

The term burner oil" is used in the present specification and claims ina generic sense to include hydrocarbon distillates heavier thangasoline. These oils are marketed under various trade names such as fueloil, furnace oil, burner oil, range oil, diesel fuel, jet fuel, etc.,and are selected to meet commercial specifications. In general, theburner oil will have an initial boiling point ranging as low as 300 F.or lower and an end boiling point which may range up to about 750 orhigher. Included in the classification of burner oil are jet fuels orother hydrocarbon distillates which may have an initial boiling point aslow as 60 F. and an end boiling point within the range of from about 450F. to about 600 F. or higher.

At the present time burner oils come primarily from non-destructivedistillation of petroleum oil, and the burner oil is commonly referredto in the art as straight run distillate, and from catalytic andnon-catalytic cracking processes, and the burner oil is commonlyreferred to in the art as cycle stock. The term cycle stock is usedbecause the burner oil is separated from a fraction which is recycled tothe cracking process for further conversion therein. Other sources ofburner oil may include those produced by the reaction of carbon monoxidewith hydrogen in the process known as the Synthesis Process,Fischer-Tropsch process, etc. Regardless of the source, burner oils,particularly when comprising blends of two or more different oils, tendto undergo discoloration and form sediment in storage, and the presentinvention is directed to a novel method of retarding this deterioration.

Because of the increasing amounts of catalytic cycle stock available atthe present time, refiners have adopted the practice of blendingcatalytic cycle stock with straight run distillate to produce burneroils. As hereinbefore set forth, these blended burner oils tend toundergo discoloration and sediment formation to an undesirable extent,and require some method of retarding this deterioration. It is apparentthat discoloration of burner oil is undesirable because many burner oilsare marketed on the basis of a color specification, and discolored oilscannot meet the color specification. Furthermore, sediment formation inburner oil is objectionable because the sediment tends to plugstrainers, burner tips, injectors, etc. and, when used as diesel fuel,tends to form varnish and sludge in the cylinders of the diesel engine.The sediment referred to herein is different from the solid materialoriginally contained in burner oils and referred to in the art as B. S.& W. The sediment with which the present invention is concerned is notcontained in the burner oil as produced but forms during storage.

While, as hereinbefore set forth, the present invention is particularlyapplicable to the treatment of blends of catalytic cycle stock andstraight run distillate, there are cases where the straight rundistillate itself or the catalytic cycle stock will undergo excessivesediment formation and discoloration in storage. It is understood thatthe present invention may be used for the purpose of retarding thisdeterioration. Similarly, the present invention may have an applicationto the treatment of lubricating oils, transformer oils, turbine oils,etc. which undergo excessive deterioration in storage.

In one embodiment the present invention relates to a method ofstabilizing a hydrocarbon distillate heavier than gasoline whichcomprises incorporating in said distillate a small amount of anitropyrimidine.

In a specific embodiment the present invention relates to a method ofretarding deterioration of burner oil which comprises incorporatingtherein from about 0.000l% to about 1% by weight of anitrohexahydropyrimidine.

In still another embodiment the present invention relates to a burneroil containing the nitropyrimidine as herein set forth as an additive toretard deterioration of the burner oil.

The additive for use in accordance with the present invention comprisesa nitropyrimidine, including nitropyrimidine, nitrodihydropyrimidine,nitrotetrahydropyrimidine and nitrohexahydropyrimidine.

The particular position of the nitro group on the pyrimidine ring Willdepend in most cases upon the particular compounds used as startingmaterials for the preparation of the nitropyrimidine compound.

In a preferred embodiment, at least one nitro group is attached to atleast one of the carbon atoms of the pyrimidine ring. In some casesnitropyrirnidine compounds having a nitro group attached to the nitrogenatom in the pyrimidine ring may be employed but not necessarily with theequivalent results.

Preferred nitropyrimidine compounds comprise 1,3-dicycloalkyl-S-nitro-5-methyl hexahydropyrimidine andl,3-dialkyl-5-nitro5-rnethyl-hexahydropyrimidine. These compounds may beprepared in any suitable manner. In one method of manufacture,l,3-dicyclohexyl-5-nitro5- methylhexahydropyrimidine may be prepared byreacting cyclohexylamine, formaldehyde and nitroethane. When dialkylsubstituted compounds are desired, the desired alkylamine is employed inplace of the cyclohexylamine. Thus for example, the alltylainine maycomprise methylamine, ethylamine, propylamine and particularlyisopropylamine, butylamine, amylamine, hexylamine, heptylamine,octylamine and particularly tertiaryoctylamine, nonylamine, decylamine,etc. Similarly, in place of cyclohexylamine, cyclopropylamine,cyclobutylamine, cyclopentylamine may be employed and, in some cases,cyclohexenenylamines, cyclohexadinenylarnines and phenyl amines may beemployed. It is understood that the cyclic amines may contain aliphaticside chains attached thereto and also that the cyclic amines and thealkyl amines may have attached thereto one or more substituentscontaining oxygen, nitrogen and/or sulfur. Thus, for example, the cyclicamine or alkyl amine may contain one or more nitro groups attachedthereto.

In place of nitroethane as a starting material for the preparation ofthese additives, other suitable nitroalkanes may be employed, includingnitromethane, nitropropane, nitrobutane, nitropentanc, nitrohexane, etc.When nitromethane is employed along with formaldehyde andcyclohexylamide, for example, the resultant pyrimidine compound will bel,3-dicyclohexyl-S-nitro-S-hexahydropyrimidine. Similarly, whennitropropane is utilized, the

pyrimidine compound will be 1,3-dicyclohexy1-5-nitro- 5-ethylhexahydropyrimidine.

It is understood that these various nitropyrimidine compounds are notnecessarily equivalent but that all of them will serve to retarddeterioration of burner oils.

The additive of the present invention generally is added to the burneroil in an amount of less than about 1% by weight and preferably fromabout 0.001% to about 1% by weight. It is understood that theseadditives may be used alone or in conjunction with other additivesemployed for specific purposes, such as metal deactivators,antioxidants, preferably of the phenolic type, synergists, cetaneimprovers, rust inhibitors, etc.

The following examples are introduced to illustrate further the noveltyand utility of the present invention but not with the intention ofunduly limiting the same.

Example 1 1,3-dicyclohexyl-5-nitro-5-methyl -hexahydropyrimidine wasprepared by reacting 99 grams of cyclohexylamine, 112.5 ml. of 36%aqueous formaldehyde and 37.5 ml. of nitrocthane, with constantstirring, at C. The product was extracted with ether, dried over sodiumsulfate, the solvent evaporated and the product was recrystallized. Theproduct had a melting point of 7980 C.

0.02% by weight of 1,3-dicyclohexyl-S-nitro-S-methylhexahydropyrimidinewas incorporated in a fuel oil blend comprising catalytically crackedand straight run fuel oil. The samples of fuel oil were subjected toaccelerated aging at 100 C. for hours, and the color of the differentsamples was determined in a Lumitron, model 402-E, Spectrophotometer.Distilled water is rated as 100 and a very dark oil is rated as 0 inthis analysis.

The fuel oil had an original color of 88. After accelerate d aging, thecolor of the fuel oil dropped to 23. The sample of the fuel oilcontaining the 1,3-dicyclohexyl- S-nitro-S-methyl-hexahydropyrimidine,after such aging, had a color of 51.

It will be noted that after the accelerated aging, the sample, to whichthe hexahydropyrimidine compound was added, was of considerably bettercolor than the sample of the fuel oil without this additive.

Example If 0.02% by weight of1,3-ditert-octyl-5-nitro-5-methylhexahydropyrimidine was added toanother sample of the fuel oil described in Example I. After theaccelerated aging, the sample containing the additive had a color of 47.Here again it will be noted that the hexahydropyrimidine compound servedto considerably retard discoloration of the fuel oil.

The 1,3-ditert-octyl-S-nitroS-methyl-hexahydropyrimidine was prepared insubstantially the same manner as described in Example I except that 129grams of tertoctylamine were utilized instead of the dicyclohexylamine.

Example Ill l,3 diisopropyl-5-nitro-5-methyl exahydropyrimidine wasprepared in the same manner as described in Example I except that 60grams of isopropylamine were used instead of the cyclohexylamine. Thisproduct had a melting point of 4445' C.

0.02% by weight of the 1,3-isopropyl-5-nitro-5-methylhexahydropyrimidinewere added to another sample of the fuel oil described in Example i and,after the acceleratcd aging, the fuel oil had a color of 43. Here againit will be noted that the color of the fuel oil was considerablyimproved by the addition of the hexahydropyrimidine compound.

Example IV 1,3-dihexyl-5-nitro -5- propylhexahydropyrimidine may beprepared by the reaction of hexylamine, formaldehyde and nitrobutane.The resultant compound may be added in a concentration of 0.05% byweight to a West Coast catalytically cracked burner oil to retarddiscoloration thereto.

I claim as my invention:

1. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufficientamount to retard said sediment formation, a nitropyrirnidine.

2. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufiicientamount to retard said sediment formation, a nitrohydropyrimidine.

3. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufficientamount to retard said sediment formation, a nitrodihydropyrimidine.

4. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufficientamount to retard said sediment formation, a nitrotetrahydropyrimidine.

5. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufiicientamount to retard said sediment formation, a nitrohexahydropyrimidine.

6. A hydrocarbon oil heavier than gasoline and nor mally subject tosediment formation in storage containing, in a small but suliicientamount to retard said sediment formation, a di-substitutednitropyrimidine in which the substituents are selected from the groupconsisting of alkyl and cycloalkyl radicals.

7. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufiicientamount to retard said sediment formation, a1,3-dicycloalkyl-5-nitro-5-methyl-hexahydropyrimidine.

8. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufficientamount to retard said sedi ment formation, a1,3-dialkyl-S-nitro-5-methyl-hexahydropyrimidine.

9. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufiicientamount to retard said sediment formation,1,3-di-cyclohexyl-5-nitro-5-methyl-hexahydropyrimidine.

10. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufficientamount to retard said sediment formation,1,3-dioctyl-5-nitro-5-methyl-hexahydropyrimidine.

11. A hydrocarbon oil heavier than gasoline and nor mally subject tosediment formation in storage containing, in a small but sufiicientamount to retard said sediment formation,1,3-diisopropyl-5-nitro-5-methyl-hexahydropyrimidine.

12. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufficientamount to retard said sediment formation,l,3-diisopropyl'5-nitro-5ethyl-hexahydropyrimidine.

13. A hydrocarbon oil heavier than gasoline and normally subject tosediment formation in storage containing, in a small but sufficientamount to retard said sediment formation,l,3-dihexyl-5-nitro-5-propyl-hexahydropyrimidine.

References Cited in the file of this patent UNITED STATES PATENTS2,391,847 Senkus Dec. 25, 1945 2,575,003 Caron et al. Nov. 13, 19512,622,018 White et al. Dec. 16, 1952

1. A HYDROCARBON OIL HEAVIER THAN GASOLINE AND NORMALLY SUBJECT TOSEDIMENT FORMATION IN STORAGE CONTAINING, IN A SMALL BUT SUFFICIENTAMOUNT TO RETARD AND SEDIMENT FORMATION, A NITROPYRIMIDINE.